Line stop assemblies have traditionally been used to temporarily prevent fluid flow through a selected pipeline section. For example, line stop assemblies may be used to complete modifications or repairs on a downstream pipeline section. Often, line stop assemblies allow such modifications or repairs to be made without any substantial interruption of service (e.g., flow of fluid, such as gas or liquid, through the pipeline section). Generally, line stop assemblies are implemented by securing a sleeve over a segment of the pipeline. A temporary valve is then installed on a supporting flange extending radially from a saddle of the sleeve. Once the valve is installed, the pipeline can be tapped, and flow may be regulated (e.g., prevented) using the temporary valve. After the necessary modifications or repairs have concluded, the temporary valve can be removed and replaced by a completion plug inserted through an axially extending bore of the supporting flange. A locking mechanism may be installed on the flange to secure the completion plug within the bore.
Conventional line stop assemblies are subject to leakage due to the inadequacy of the seal between components. Additionally, the performance of locking mechanisms disposed in a radial bore of the line stop assembly may be affected if the locking components are not properly aligned (disposed substantially concentric to the radial bore).